Altimeter



June 12, 1945. A EE $378,226

ALTIMIETER' Filed Nov. 20, 1943' mousmw FEET INVENTOR. ABA PEN LEE iroe/vs rs Patented June 12, 1945 UNITED STATES PATENT OFFICE ALTDHETER Asa Ben Lee, Cleveland, Ohio, assignorto Designers For Industry, Inc., Cleveland, Ohio, a

corporation of Ohio Application November 20, 1943-, Serial No. 511,166

6 Claims.

This invention relates to indicating instruments and as one of its objects aims to provide a novel form of indicating instrument which is responsive to changes in the pressure of a fluid and with which such changes can be indicated in a direct and accurate manner.

Another object of my invention is to provide a novel indicating instrument containing a meter and a control or actuating means therefor em bodyin an electron tube which is responsive to changes in the pressure'of the atmosphere or other fluid.

A further object of my invention is to provide a novel indicating instrument of the character mentioned which is well suited for use as analtimeter on aircraft of variouskinds.

being used in that connection wherein the change in fluid pressure is a change in the pressure of the atmosphere due to a change in altitude. As shown in the drawing, the altimeter comprises a meter or indicator I and an electron tube apparatus I I' for actuating or controlling the meter.

The apparatus II includes an electron tubev l2 which is connected with a static tube I3 by the conduit I4 and, as explained more in detail herewall portion which in this instance is in the form of a hollow diaphragm device or bellows I9. The diaphragm device I9 may be formed of a thin flexible sheet material, such as beryllium-copper alloy, and has a sealed connection with the envelope I5 of the electron tube so that the chamber of the diaphragm device will be in direct communication with the interior of the electron tube The diaphragm device I! is located in a housing 22 which is connected through the passage 2|.

with the static tube I3. by the conduit I4.

- During use of my indicatingl instrument as an altimeter on an aircraft, the changes occurring in the pressure of theatmosphere due to changes in altitude will be transmitted to the housing 22 through the conduit I4 and will act on the sure is lower and permits the diaphragm device inaiter, responds to changes in the pressure of the atmosphere due to changes in altitude. The static tube I3 is represented as being of a conventional form used on aircraft.

The electron tube I2 comprises a sealed casing or envelope l5 having a plate It and a cathode II' therein. The envelope I2 also contains a heater I8 for heating ,the cathode in the usual manner for the purpose of producing a, flow of electrons from the cathode to the plate. In constructing the electron tube I2 the envelope I5 is evacuated and a small amount of a suitable gas, such as neon gas, is introduced into and sealed in the tube.

-As mentioned above the electronltube I2 is responsive to changes in the pressure of the atmosphere and. to this end, is provided with a flexible outer surface of the diaphragm device It. At low altitude the pressure of the atmosphere, is relatively greater and tends to collapse the diaphragm device I9 thereby forcing more of the confined gas into the envelope I5 of the electron tube and thus increasing the gas pressure in the latter. At higher altitudes the atmospheric pres- I 9 to-expand thus allowing some of the gas to flow out of the electron tube I2 thereby reducing the pressure of the gas in the envelope I5. The flow of electrons from the cathode I! to the plate I I6 varies as the gas pressure changes Within the envelope I5, the flow being relatively greater when the gas pressure is low and relatively smail er when the gas pressure is increased.

As shown in the drawing, conductors 2 and 25 are connected respectively with the plate Iii and cathode I 'I and provide a plate circuit or output circuit to which a plate voltage of appropriate value may be applied from any suitable A pair of conductors 26 connect the source. heater I8 with a suitable source of heating current. The electric meter I0 is connected with the electron tube as by means of an inductive coupling or transformer 21 havingone of its coils 28 located in the plate circuit and the other coil 29 connected in circuit with the meter by the conductors 30 and 3|. The useof the coupling 21 in the plate circuit permits the voltage differential to be maintained for all altitudes and, in addition, this coupling serves as an electrostatic shield between the electron tube apparatus II and the meter or meters I0.

The meter III may be any standard or conventional form of electric meter, such as a galvanometer, having a pointer or needle 32 which is deflected'through variable distances depending upon the current or voltage values supplied-thereto by the conductors to and 3|. The meter is also pi vided with a series of graduations or indications 33 with which the movable pointer 82 cooperates. In this instance the graduations represent altitude measurements in thousands of feet, although the meter could be provided with other scales or markings. v

For purposes of calibrating, the plate circuit of the electron tube 52 contains a variable resistance orpotentiometer 36 by which the operation or the meter can be adjusted with respect to the functioning of other parts of the indicating apparatus or with respect to the characteristics or" the aircraft or various other factors. Such calibration is also necessitated by the fact that some current must flow in the plate circuit at all.

times even when the reading of the meter I8 is zero.

Although I have shown only one meter ill in the drawing, a plurality of such meters can be energized or controlled by the electron tube apparatus ii and can be located at various desired points on the aircraft. Such additional meters would be connected with the coil 2i! by simply extending the condutcors 3S and 3!.

irom the foregoing description and the accompanying drawing, it will now be readily understood that I have provided a novel form of indieating instrument by which the direction and extent or change in the pressure of a fluid can be visibly indicated in a sensitive and accurate manner. It will be seen also that by novel indicating instrument is especially suitable for use as an altimeter on various kinds of aircraft.

While I have illustrated and described my indicatinginstrumerit in more or less detail, it will be understood, of ccurse that I do not wish to be correspondingly limited, but regard my invention as including all changes and modifications coming within the scope of the appended claims. Having thus described my invention, I claim: 1. An instrument of the character described comprising, an electron tube having gas sealed therein and whose electrical output varies in response to changes in the gas pressure in said tube, said tube having a. flexible wall portion, an indicator electrically connected with said tube so as to be responsive to variations in said electrical output, and fluid pressure transmitting 'aeraeee be flexed for varying the gas pressure in the tube, and a meter electrically connected with said tube so as to be responsive to variations in its electrical output.

3. An altimeter comprising, an electron tube having gas sealed therein and whose electrical output varies in response to changes in the gas pressure in the tube, an indicator electrically connected with the tube so as to be responsive to variations in its electrical output, said tube having a wall portion adapted to be. flexed for varying the pressure of the gas in the tube, means connected with said tube so as to form a chamher for enabling fluid pressure changes to act on said wall portion, and conduit means connected with said chamber and adapted to transmit fiuid pressure changes thereto in response to changes in atmospheric pressure.

4. An instrument of the character described comprising, an electron tube having a sealed envelope containing gas and whose electrical out put varies in response to changes in the gas pressure in the envelope, said envelope including a hollow flexible member, a housing for said holconnected with said tube so as to be responsive to variations in its electrical output.

5. An instrument for an aircraft having a static tube comprising, an electron tube having a sealed envelope containing gas and whose elec- -rical output varies in response to changes in the gas pressure in the envelope, said envelope including a flexible wall portion, a meter electrically connected with said electron tube so as to be responsive to variations in the electrical output thereof, means connected with said tube so as to form a chamber for enabling fluid pressure to act on said wall portion, and means connecting said chamber with said static tube so that pressure changes in the latter will act through said wall portion to cause variations in the electrical output of said electron tube.

6. An instrument for an aircraft having a. static tube comprising, an electron tube having gas sealed therein and whose electrical output varies in response to changes in the gas pressure therein, a meter electrically connected with said electron tube so as to be responsive to variations in its electrical output, said electron tube having a flexible wall portion, and means connecting said electron tube with said static tube so that pressure changes in the latter will act through said flexible wall portion to cause corresponding changes in the pressure of the gas in said electron tube.

ASA REN LEE. 

